public interface Box {
    // instances represent rectangular boxes
    //   consisting of printable characters
  void print();
    // writes several lines representing
    //   the box "this" to standard output
  void setSize(int width, int height);
    // 3 <= width <= 40; 3 <= height <= 10 (preconditions)
    // sets the size of the frame of the box
  void setFrameChar(char fc);
    // the frame of the box consists of fc
}
